The objective of this study is to examine myocardial and coronary adrenergic receptor function in the neonatal lamb and to identify alterations which may occur in acutely and chronically diabetic animals. Effects of insulin will be determined in normal and insulin deficient lambs. Effects of lactic acidosis and ketoacidosis will be examined. Acute diabetes mellitus will be induced by giving aloxan monohydrate (150 micrograms/kg). This causes progressive hyperglycemia and hyperlipidemia, with the appearance of ketoacidosis within 2-4 days. One to 4 days after alloxan, left ventricular performance will be measured by obtaining ventricular function curves and measuring LV dP/dt max under controlled hemodynamic conditions. Simultaneous measurements of coronary flow, MVO2 and substrate uptake will be done. Alpha receptor sensitivity will be tested through 2 the application of dose-response curves following graded doses of methoxamine. Effects of blockade with phentolamine will also be studied. Beta receptor function will be similarly assessed by the use of isoproterenol stimulation and practolol (4 micrograms/kg) blockade. Relative tonic cardiac sympathetic discharge will be assessed from the changes following ganglionic blockade with TEAC. Normal age-matched controls will be compared with acutely diabetic lambs, with or without ketoacidosis. Chronic diabetics (1-2 months) will be prepared by repeated injections of smaller doses of alloxan until a stable diabetic state (glucose greater than 200 micrograms/dl) is achieved. Glucose tolerance curves and insulin levels will be obtained. They will be studied in the same protocol as described for the acute diabetics.